This invention relates generally to a wear plate for use in the side frame structure of a railway truck. A typical railway car is supported by two trucks with one truck supporting each end of the car. Each truck consists of a pair of parallel pedestal side frames, each side frame having two downwardly opening jaws. The side frames are connected together by bolsters to form a substantially rectangular frame structure on which the car sits. This frame structure rides on wheels that are supported by bearing assemblies located in each of the jaws.
Each bearing assembly consists of a roller bearing adapter that is free to slide in the vertical direction relative to the jaw. The roller bearing adapter rests on a roller bearing that, in turn, rotatably supports the axles that carry the wheels.
The lateral and longitudinal movement of the adapter within the jaw in constrained by a pair of lugs, located on the jaw walls, that are engageable with a pair of mating channels formed in the roller bearing adapter. However, because of necessary design tolerances, some clearance remains between the mating components. As a result, the roller bearing adapter is able to slide relative to the side frame causing objectionable wear on the pedestal jaw roof and adapter crown.
In addition to the wear on the pedestal jaw roof and adapter crown, an objectionable amount of wear also occurs on the outboard lug. This wear results when the braking force that is applied to the wheel forces the adapter into contact with the outboard lug such that the adapter rubs against the lug.
Wear plates have been designed that can be inserted between the roller bearing adapter and the pedestal to protect the pedestal jaw roof and adapter crown. However, certain wear plates are made undesirably rigid by the means employed to fix the wear plate in the proper position. Some methods of attachment can generate areas of high stress in the wear plates rendering them susceptible to fracturing under the shifting loads caused by the movement of the bearing unit within the pedestal jaw. Once the integrity of the wear plate breaks down, the wear plate may be able to move from its proper position thereby reducing the amount of protection provided. Moreover, the uneven surface of a cracked wear plate can actually increase the wear on the adapter and side frame.
Furthermore, the railroad industry has not developed a protective device for the outboard lug, having instead to rebuild the worn lug by a welding process. This rebuilding process is a slow and expensive operation that requires the truck to be idled and dismantled while it is performed.
Therefore, it is apparent that there is a need in the railway industry for a wear plate that can protect the adapter crown, pedestal jaw roof and outboard lug.